The present invention relates to a method for producing support elements in the ground, in which a hole is sunk through non-stable ground at least to load bearing ground and filled with a load bearing material. The invention also relates to an apparatus with a twist drill for performing the method.
It is necessary to have support elements in the ground, where structures cause loads in the ground which cannot be borne by the naturally occurring soil. The introduced support elements, which pass either down to the load bearing ground or into the latter, bridge the not stable soil and constitute a connecting member between the structure and the fixed geology. The structure can be constituted both by traffic links and buildings.
For example in connection with road building, it is known to completely remove the non-load bearing soil and replace it by load bearing material. In addition, support elements are used, which comprise bored piles or piling poles which, as a function of their number and diameter, extend onto the load bearing soil or are bound in the latter. Moreover a soil improvement or replacement method is used, in which the not load bearing soil is tamped by vibration and in this way is transformed into a stable subsoil. A further consolidation can be achieved in this way by adding ballast. If the tamping of the soil is carried out without a prior drilled hole, into which the material to be tamped is filled, a foundation of the support element on the load bearing soil can still be achieved. However, under these conditions, in many cases the desired and required supporting effect cannot be achieved. This disadvantage also appears in another method, in which the non-load bearing soil is improved or replaced by chemical injection, e.g. a high pressure cement injection.
Thus, in the known methods, openings are normally made through the non-load bearing ground and, following this, the support elements are introduced. In most cases these openings must be tubed, which leads to high labour expenditure.